It's actually worse than that.
AC will fry all the electronics in a modern engines circuit board.
So yes, D&H 65 is right, they convert the AC to DC, and they do it in varying voltages.
The Motor uses up to 12 VDC but the circuit boards are mostly 3VDC now, some older ones were 5VDC.
You don't give the number of the engine so I can't be specific at all.
A DCRU-WD board is Lionel Specific but even within those there are variants.
I suspect the engine should be referred to a repair person with Factory training.
I'm an electronic engineer and I won't touch it because I can't get the documentation needed to do the job right.
I send my engines in to be repaired Or I replace the entire board.
Simple stuff like smoking cars I will fix, no big deal, but engines are a whole higher level.
